The inventive concept relates to semiconductor devices and methods of fabricating the same. In particular, the inventive concept relates to three-dimensional semiconductor memory devices, having vertical channels, and methods of fabricating the same.
In general, many kinds of layers are formed by deposition and patterning processes on a substrate in the manufacturing of semiconductor memory devices. In the case of a three-dimensional semiconductor memory device such as a vertical NAND flash memory, many different kinds of layers, namely, insulating and conductive layers, need to be formed one atop the other on the upper surface of a substrate, and openings through these layers need to be formed and filled to produce features of the device such as the vertical channels. The substrate should remain relatively planar or flat throughout the course of the fabrication process to prevent process failures and poor electrical characteristics.